diff -r 05db41701ece -r efbbc2f9121e mercurial/cext/revlog.c
--- a/mercurial/cext/revlog.c	Mon Nov 07 22:12:59 2022 -0500
+++ b/mercurial/cext/revlog.c	Sun Nov 06 16:56:23 2022 -0500
@@ -1446,16 +1446,25 @@
 static PyObject *index_findsnapshots(indexObject *self, PyObject *args)
 {
 	Py_ssize_t start_rev;
+	Py_ssize_t end_rev;
 	PyObject *cache;
 	Py_ssize_t base;
 	Py_ssize_t rev;
 	PyObject *key = NULL;
 	PyObject *value = NULL;
 	const Py_ssize_t length = index_length(self);
-	if (!PyArg_ParseTuple(args, "O!n", &PyDict_Type, &cache, &start_rev)) {
+	if (!PyArg_ParseTuple(args, "O!nn", &PyDict_Type, &cache, &start_rev,
+	                      &end_rev)) {
 		return NULL;
 	}
-	for (rev = start_rev; rev < length; rev++) {
+	end_rev += 1;
+	if (end_rev > length) {
+		end_rev = length;
+	}
+	if (start_rev < 0) {
+		start_rev = 0;
+	}
+	for (rev = start_rev; rev < end_rev; rev++) {
 		int issnap;
 		PyObject *allvalues = NULL;
 		issnap = index_issnapshotrev(self, rev);